In the central nervous system, oligodendrocytes ensheath and wrap axons in many concentric layers of myelin, a process that is essential for efficient electrical signaling in axons. In diseases such as multiple sclerosis and cerebral palsy, oligodendrocytes fail to form compact myelin and proper distal localization of myelin basic protein (MBP) is absent. MBP is the most highly expressed mRNA in oligodendrocytes by over 10-fold. It is also a special protein who's mRNA must be transported to distal processes of oligodendrocytes before it can be translated. The mechanism and in vivo function of MBP mRNA transport, however, has remained elusive. This project aims to determine whether regulation of MBP mRNA transport at the cargo level is necessary for myelination. In order to visualize MBP mRNA transport in living primary oligodendrocytes, modern imaging tools, such as the RNA-binding reporter protein MS2, will be developed for the detection and analysis of MBP mRNA motility. Furthermore, two independent mass spectrometry approaches will be used to identify proteins in the MBP mRNA granule that are involved in its transport. Regulators of transport are often scaffolding proteins that have the ability to bind to multiple motor proteins. Thus, candidate regulators of MBP mRNA transport will be confirmed via their ability to associate with motor proteins as well as with siRNA knockdown strategies. Finally, two different mouse models will be made to determine whether MBP mRNA transport is necessary for myelination in vivo. The proposed project will elucidate how motor proteins associate with mRNA cargos and identify the molecular mechanism underlying a pivotal process in oligodendrocyte maturation and myelination and will have important implications for the fields of glial cell biology, molecular motors, RNA protein biology, and myelin diseases. Importantly, since distal MBP protein expression and compact myelin formation fail in myelinating diseases, these findings may reveal novel therapeutic targets for stimulating myelination in disease.